Someone call . . . . . . . . policeman! A. a B. an C. the D. no article

The correct answer is: D. no article

The word “policeman” is a common noun, which means it refers to any member of the police force. Common nouns are not preceded by articles unless they are specific or unique. In this case, the speaker is not referring to a specific policeman, but rather any policeman who is available to help. Therefore, the article “a” or “an” would not be appropriate. The article “the” would also be incorrect, because it is used to refer to a specific person or thing.

Here are some examples of when an article would be appropriate:

• I saw a policeman walking down the street.
• I called the police when I saw the crime.

In these examples, the speaker is referring to a specific policeman (the one they saw walking down the street) or a specific police department (the one they called).